1. Field of Invention
The present invention relates to a liquid crystal display (LCD). More particularly, the present invention relates to an LCD array substrate and its manufacturing method.
2. Description of Related Art
With progress in LCD technology and an increased demand for large-scale displays, both the size and resolution of LCD screens are continually increasing. An increase in both the resistance and the capacitance of the conductive lines of the LCD is required to increase the LCD resolution. Increasing the resistance and the capacitance of the conductive lines worsen the resistance-capacitance time delay (RC delay) problem in LCD. The RC delay problem affects both signal transfer in the LCDs and the LCD display quality.
Traditional methods to reduce RC delay mainly include using a copper process and broadening the width of the conductive lines. The resistance of the conductive line can be reduced to improve the signal transfer rate by introducing the copper process of manufacturing copper conductive line to the LCD manufacturing processes. Therefore, the RC delay is also reduced. However, the copper process has many problems remained to be solved. Another method to solve the RC delay problem is to broaden the width of the conductive lines. The cross-sectional area of the conductive lines is increased by broadening the width of the conductive lines. Therefore, the resistance of the conductive lines is decreased, and the RC delay is reduced. However, the size of the pixel areas is influenced by broadening the conductive line width, and thus the aperture ratio and the brightness of the LCDs are decreased.
Each LCD pixel area is composed of many different functional thin layers. Each thin layer has a different reflective index. The reflective index for each thin layer is different from the reflective indices for the other thin layers. Because different thin layers have different reflective indices, when light passes through interfaces of the different thin layers, a portion of the light is easily reflected, and the transmittance of the light is decreased. Therefore, the brightness of the LCDs is decreased. The LCDs need to use high brightness backlight modules to generate the required display brightness.